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G-SYNC 101: Control Panel

Published Jun 20, 2017 by in: G-SYNC

G-SYNC Module

The G-SYNC module is a small chip that replaces the display’s standard internal scaler, and contains enough onboard memory to hold and process a single frame at a time.

The module exploits the vertical blanking interval (the span between the previous and next frame scan) to manipulate the display’s internal timings; performing G2G (gray to gray) overdrive calculations to prevent ghosting, and synchronizing the display’s refresh rate to the GPU’s render rate to eliminate tearing, along with the delayed frame delivery and adjoining stutter caused by traditional syncing methods.

G-SYNC Demo

The below Blur Busters Test UFO motion test pattern uses motion interpolation techniques to simulate the seamless framerate transitions G-SYNC provides within the refresh rate, when directly compared to standalone V-SYNC.

G-SYNC Activation

“Enable for full screen mode” (exclusive fullscreen functionality only) will automatically engage when a supported display is connected to the GPU. If G-SYNC behavior is suspect or non-functioning, untick the “Enable G-SYNC, G-SYNC Compatible” box, apply, re-tick, and apply.

Blur Buster's G-SYNC 101: Control Panel

G-SYNC Windowed Mode

“Enable for windowed and full screen mode” allows G-SYNC support for windowed and borderless windowed mode. This option was introduced in a 2015 driver update, and by manipulating the DWM (Desktop Windows Manager) framebuffer, enables G-SYNC’s VRR (variable refresh rate) to synchronize to the focused window’s render rate; unfocused windows remain at the desktop’s fixed refresh rate until focused on.

G-SYNC only functions on one window at a time, and thus any unfocused window that contains moving content will appear to stutter or slow down, a reason why a variety of non-gaming applications (popular web browsers among them) include predefined Nvidia profiles that disable G-SYNC support.

Note: this setting may require a game or system restart after application; the “G-SYNC Indicator” (Nvidia Control Panel > Display > G-SYNC Indicator) can be enabled to verify it is working as intended.

G-SYNC Preferred Refresh Rate

“Highest available” automatically engages when G-SYNC is enabled, and overrides the in-game refresh rate selector (if present), defaulting to the highest supported refresh rate of the display. This is useful for games that don’t include a selector, and ensures the display’s native refresh rate is utilized.

“Application-controlled” adheres to the desktop’s current refresh rate, or defers control to games that contain a refresh rate selector.

Note: this setting only applies to games being run in exclusive fullscreen mode. For games being run in borderless or windowed mode, the desktop dictates the refresh rate.

G-SYNC & V-SYNC

G-SYNC (GPU Synchronization) works on the same principle as double buffer V-SYNC; buffer A begins to render frame A, and upon completion, scans it to the display. Meanwhile, as buffer A finishes scanning its first frame, buffer B begins to render frame B, and upon completion, scans it to the display, repeat.

The primary difference between G-SYNC and V-SYNC is the method in which rendered frames are synchronized. With V-SYNC, the GPU’s render rate is synchronized to the fixed refresh rate of the display. With G-SYNC, the display’s VRR (variable refresh rate) is synchronized to the GPU’s render rate.

Upon its release, G-SYNC’s ability to fall back on fixed refresh rate V-SYNC behavior when exceeding the maximum refresh rate of the display was built-in and non-optional. A 2015 driver update later exposed the option.

This update led to recurring confusion, creating a misconception that G-SYNC and V-SYNC are entirely separate options. However, with G-SYNC enabled, the “Vertical sync” option in the control panel no longer acts as V-SYNC, and actually dictates whether, one, the G-SYNC module compensates for frametime variances output by the system (which prevents tearing at all times. G-SYNC + V-SYNC “Off” disables this behavior; see G-SYNC 101: Range), and two, whether G-SYNC falls back on fixed refresh rate V-SYNC behavior; if V-SYNC is “On,” G-SYNC will revert to V-SYNC behavior above its range, if V-SYNC is “Off,” G-SYNC will disable above its range, and tearing will begin display wide.

Within its range, G-SYNC is the only syncing method active, no matter the V-SYNC “On” or “Off” setting.

Currently, when G-SYNC is enabled, the control panel’s “Vertical sync” entry is automatically engaged to “Use the 3D application setting,” which defers V-SYNC fallback behavior and frametime compensation control to the in-game V-SYNC option. This can be manually overridden by changing the “Vertical sync” entry in the control panel to “Off,” “On,” or “Fast.”

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3195 Comments For “G-SYNC 101”

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retrospek
Member
retrospek

My monitor is 280hz but whenever i use gsync + vsync with reflex on it limits my fps to 260. should i instead use incame fps cap of 277 and turn off reflex and instead use low latency on ultra?

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16 hours 45 seconds ago
jorimt
Author
jorimt

My monitor is 280hz but whenever i use gsync + vsync with reflex on it limits my fps to 260.

That’s expected; it’s the Reflex auto limiter to ensure the framerate remains well within the G-SYNC range.

should i instead use incame fps cap of 277 and turn off reflex and instead use low latency on ultra?

See my Optimal G-SYNC settings:
https://blurbusters.com/gsync/gsync101-input-lag-tests-and-settings/14/

If you have any remaining questions after, reply here.

Like1Vote Down 
10 hours 46 minutes ago
ThanksJorimt
Member
ThanksJorimt

I noticed in your LDAT testing reflex had the same input lag (16ms) but at a lower 224 fps than in-game frame limiter alone (237 fps). Is there a reason to use reflex when it seems like you’re paying a -13 fps penalty for effectively the same result.

Also, just a small typo I noticed on the last page (14):

… ~224 FPS @240Hz (etc) whenever the framerate can be sustained above the refesh rate, and 2) dynamically monitor and limit the framerate whenever it can’t be sustained above the refresh rate …

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2 days 1 hour ago
jorimt
Author
jorimt

Is there a reason to use reflex when it seems like you’re paying a -13 fps penalty for effectively the same result.

Yes; for the purpose of avoiding maxed GPU usage, a manual FPS limit is static, whereas Reflex is dynamic, and will automatically keep the limit slightly below the currently achievable average framerate to prevent extra render queue latency (separate of sync latency).

As such, Reflex is most useful if a constant average framerate can’t be guaranteed, if it can, a manual limit will suffice just as well.

Finally, as for the -3 FPS vs. -13 FPS offset, the higher the physical refresh rate, the lower the limit with Reflex. Nvidia has never explicitly detailed why, but the going assumption is it’s to account for the increased frametime jitter as the maximum refresh rate becomes higher (more impactful at 360Hz and above).

The -3 FPS recommendation is just a blanket minimum starting point.

Also, just a small typo I noticed on the last page (14)

Fixed.

Like1Vote Down 
1 day 23 hours ago
voicon
Member
voicon

so in summary what is the best setting for input lag (If I turn off Gsync and also Vsync)

Like0Vote Down 
2 days 15 hours ago
jorimt
Author
jorimt

This article is for optimal G-SYNC settings, not G-SYNC off.

That said, G-SYNC off + V-SYNC off eliminates the possibility of sync latency, so the only render-related latency left in that scenario is 1) frametime latency, which is dictated by the achievable average framerate (the higher the average framerate, the lower the average frametime = the faster the frame delivery), and 2) render queue latency, which is dependent on the GPU usage percentage.

So for the lowest latency G-SYNC off + V-SYNC off, ensure your monitor is at its highest possible physical refresh rate + your system reaches the highest average framerate that doesn’t max GPU usage in the given game, and if/when it does, prevent it by enabling Reflex, where available, or setting a manual FPS limit that keeps the GPU usage below 99%.

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2 days 12 hours ago
Dvrgg
Member
Dvrgg

Hello, I wanted to ask, is it worth using the Rtss fps limit for the game (-3 fps from 165 Hz monitor), if the frame rate is not perfectly smooth when using the internal limiter? (G-sync + V-sync, -3 fps) And also, is there any point in enabling Reflex/Llm if the GPU is not loaded by 99%? Do I need to do anything else to achieve maximum smoothness even sacrificing input lag?

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6 days 14 hours ago
jorimt
Author
jorimt

is it worth using the Rtss fps limit for the game (-3 fps from 165 Hz monitor), if the frame rate is not perfectly smooth when using the internal limiter? (G-sync + V-sync, -3 fps)

If the frametime instability is being caused directly by the in-game limiter, then an RTSS limit can can improve this. If the instability is being caused by the general system/engine performance separate of the limiter, then it won’t.

This can be game-dependent, so you’ll need to try each.

is there any point in enabling Reflex/Llm if the GPU is not loaded by 99%?

Since Reflex/LLM only further reduce latency whenever the game is GPU-bound, not strictly, no.

Do I need to do anything else to achieve maximum smoothness even sacrificing input lag?

Maximum smoothness regardless of input lag (discounting any unavoidable system-side stutter) would actually be more like G-SYNC off + V-SYNC on + framerate sustained above the refresh rate 100% of the time + 3 or more pre-rendered frames (aka allow the GPU to reach 99%).

More buffering typically = increased smoothness with higher latency, whereas less buffering typically = lower input latency with the potential of decreased smoothness. It’s very difficult to achieve a perfect balance of both. Properly configured G-SYNC comes closest.

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6 days 8 hours ago
2xmos
Member
2xmos

Hello, I got a question

You advice to set at -3 FPS on games without Reflex but Reflex cap at -7%, so why don’t you advice to set to -7%?

Thanks

Like0Vote Down 
7 days 9 minutes ago
jorimt
Author
jorimt

My -3 FPS recommendation predates Reflex by several years.

As for why I don’t recommend -7%, this is because 1), the offset of the Reflex auto limiting behavior is dependent on the current max refresh rate (the higher the refresh rate, the higher the percentage is), and 2) my recommended -3 FPS is a blanket minimum limit intended as a general starting point.

My previous test show that even at 240Hz, the average in-game and external limiter can typically keep G-SYNC engaged with a mere -2 to -3 FPS in limit in most cases, but yes, at higher refresh rates (especially 360Hz+), a lower than -3 FPS limit may (or may not) be necessary.

Regardless, my general -3 FPS minimum limit recommendation still stands as a starting point for the average setup.

Like0Vote Down 
6 days 22 hours ago
wpDiscuz

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